Regular spray foam vs fire retardant

[PigPen]

What are you guys using?

I'm looking at the kits on ebay and for 600BF, regular is about $582 and the same kit but with fire retardant foam is about $50 more.

Thoughts?

[Iceni John]

What do you want - fire retardant or thermal insulation? Just bear in mind what happened in London recently: insulation often is horribly flammable.

John

[PigPen]

They both have the same r-value. Just one is fire retardant and the other isn't.

I just couldn't decide if it made sense to worry about fire retardant foam. My thinking was that with the metal barrier on the outside, the only way the foam catches on fire is from a fire thats already on the inside of the bus.

From what I can tell looking through build threads, no one is worried about their insulation catching on fire. Just wanted to check before buying...